An important requirement of dense wavelength-division multiplexed (DWDM) systems is the generation of wavelengths that are closely spaced—usually spaced evenly. Most DWDM systems generate such closely spaced wavelengths by employing multiple discrete lasers at a rate of one per wavelength. For example, in a 100 channel DWDM system, a bank of 100 discrete lasers is employed to generate the 100 different channels. However, such systems are expensive and further do not allow for the close spacing of optical channels. Channel spacing in state-of-the-art DWDM systems based on a bank of discrete lasers, is currently limited to 25 GHz. Therefore, the spectral utilization efficiency of such systems is poor.
Thus, it is desirable to achieve a tunable multiwavelength source that allows for precise wavelength spacing for DWDM applications, and has the advantages of superior spectral efficiency, cost, and simplicity.